This invention relates to surface winding and unwinding of cloth or plastic webs and the like from web rolls, and more particularly to support rolls having raised areas arranged discontinuously thereon for preventing wrinkles, indentations and uneven tensioning of the webs.
Many efforts have been made to avoid wrinkling of cloth being unwound from rolls on surface winders and unwinders, batchers, cradle let-offs and the like. In the area where the support rolls engage the cloth roll, the cloth roll is indented presenting a shorter cloth roll radius at that point than the radius in the unengaged areas of the roll resulting in the formation of a bulge or bagging down in advance of the support roll. Sometimes, the bulge or loose pucker resulting from such bagging down advances entirely about the wound roll causing wrinkling, marking and uneven tension.
U.S. Pat. Nos. 1,738,170, 3,433,429 and 4,026,487 illustrate effort to solve the problem through compressible support roll coverings wherein an effort is made to match the compressibility of the support roll to the compressibility of the wound web roll. An inflatable support roll covering is illustrated in Canadian Patent No. 653,299. Other efforts to solve the problem include uniform or continuously spaced fluting on the support rolls. Such fluting may be skewed or spiralled in respect to the longitudinal axis. A roll having spaced segments is illustrated in U.S. Pat. No. 1,093,913, whereas U.S. Pat. No. 3,239,163 illustrates uniformly spaced compressible fluting having upper surface areas conforming to the curvature of the flexible roll.
Attempts to match or otherwise utilize the relative compressibility of the support rolls in relation to the compressibility of the wound rolls have met with limited success. Fluted rolls having uniform circumferential spacing result in vibration or and chattering and sometimes mark the wound rolls with the pattern of the fluted segments due to the limited areas of support offered thereby.
Because of the problems outlined above, there is no cloth winder in common use which is also capable of unwinding.